1. Technical Field of the Invention
The present invention relates to a deformation processing apparatus for correcting runout caused in the surface of an armature in a clutch hub which is used for a power transmission device.
2. Related Art
For example, an electromagnetic clutch is used in connecting a compressor of an air conditioner installed in an automobile to an engine that serves as a drive source. An electromagnetic clutch is configured such that an armature of a clutch hub faces a rotor rotated and driven by an engine, and that an inner hub is connected to a compressor-side drive shaft. The armature is attracted to the rotor by an electromagnetic force, while torque is transmitted to the compressor via the inner hub that integrally rotates with the armature.
FIG. 1 is a schematic diagram illustrating a clutch hub. As shown in FIG. 1, a spline shaft of a compressor is ensured to engage with a spline hole 102 which is positioned at the center of a hub member 101. An armature 103 has an annular shape and is riveted to an outer periphery of the hub member 101. In this case, if the accuracy of dimension and the accuracy of assemblage are insufficient, the axis of the hub member 101 will be inclined when the armature 103 is assembled to a rotor. In other words, runout will be caused in an armature surface 104 when the hub member 101 turns around on the axis of the hub member.
That is to say, in order to effectively transmit torque, the armature surface 104 is required to be perpendicular to the spline shaft (i.e. normal line D with respect to an inner end face C of the spline hole 102). Accordingly, as shown in FIGS. 2A and 2B, when runout is caused in the armature surface 104 of the clutch hub (in other words, when the axis of the hub member 101 is inclined), a process of grinding the end surface of the armature 103 and removing the runout has conventionally been performed to suppress the runout so as to be lower than a standard value.
As conventional art, JP-A-H06-291475 discloses a method of performing high-spin deformation processing, instead of performing cutting or grinding, in the course of manufacturing a chassis used for a precision apparatus, so that accuracy of dimension is obtained in a processed sheet-metal product or in a molded product. Specifically, in this method, a mounting seat is provided to a sheet-metal chassis so as to be projected therefrom, followed by pressing a pressing member, which makes a conical runout motion, against the projected surface, thereby reducing the surface level to a predetermined level.
FIGS. 2A and 2B shows a deformation processing method for correcting surface runout of a clutch hub, which is based on conventional grinding, and a relationship between amount of runout and processing time. As shown in FIGS. 2A and 2B, in correcting surface runout using grinding, the amount of grinding increases as the amount of runout is increased. Therefore, a lot of time is spent for the processing, drastically reducing the productivity. On the other hand, while the technique disclosed in JP-A-H06-291475 is effective in entirely reducing the level of a projected portion, it is not suitable for correcting runout in the armature surface of a clutch hub.
It is thus desired to provide an apparatus for correcting surface runout, which is able to accurately and quickly correct runout caused in the armature surface of a clutch hub to enhance productivity.